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sotid

Section: C Library Functions (3)
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NAME

sotid - library for computing site displacements due to solid Earth tides

SYNTAX

SOTID_SET ( GEN_LOVE, MODEL_2D, ORDER_2D, ZERO_FREQ_LOVE, MODEL_3D, TIDCNF, IUER )
         INCLUDE   'sotid_type.i'
         TYPE ( TIDCNF__STRU ) ::  TIDCNF
         INTEGER*4  GEN_LOVE, MODEL_2D, ORDER_2D, ZERO_FREQ_LOVE, MODEL_3D, IUER

SOTID_PRE ( L_STA, C_STA, R_CFS, TIDCNF, STATID, IUER )
         INCLUDE   'sotid_type.i'
         INTEGER*4  L_STA, IUER
         CHARACTER  C_STA(L_STA)*(SOTID__NAM_LEN)
         REAL*8     R_CFS(3,SOTID__MAX_STA)
         TYPE ( STATID__STRU ) ::  STATID(L_STA)
         TYPE ( TIDCNF__STRU ) ::  TIDCNF

SOTID_TIM ( MJD, TAI, UT1_M_TAI, TIDCNF, TIMTID, IUER )
         INCLUDE   'sotid_type.i'
         INTEGER*4   MJD, IUER
         REAL*8      TAI, UT1_M_TAI
         TYPE ( TIDCNF__STRU ) ::  TIDCNF
         TYPE ( TIMTID__STRU ) ::  TIMTID !

SUBROUTINE SOTID_DSP ( TIDCNF, TIMTID, STATID, D_REN )
         INCLUDE   'sotid_type.i'
         REAL*8     D_REN(3)
         TYPE ( TIDCNF__STRU ) ::  TIDCNF
         TYPE ( TIMTID__STRU ) ::  TIMTID
         TYPE ( STATID__STRU ) ::  STATID !

FUNCTION SOTID_INQ ( REQUEST, TIDCNF, OUT_STR, OUT_STR_LEN, IUER )
         INCLUDE   'sotid_type.i'
         INTEGER*4  SOTID_INQ
         TYPE ( TIDCNF__STRU ) ::  TIDCNF
         INTEGER*4  REQUEST, OUT_STR_LEN, IUER
         CHARACTER  OUT_STR*(*)
      END  FUNCTION  SOTID_INQ

DESCRIPTION

Subroutine sotid_set sets configuration for sotid software. Values of each configuration parameter are checked and if the checks are OK, they are put in the field of the object TIDCNF. Configuration parameters defines:

: -- which generalized Love numbers are to be used;
: -- which model for the Love numbers of the second degree is to be applied;
: -- tidal waves of which order of the second degree should be taken into account: zonal, diurnal, semi-diurnal or their combination. Normally, all orders, zonal, diurnal, semi-diurnal are used.
: -- which Love numbers for the tides of the zeroth frequency should be used;
: which model for the Love numbers of the third degree is to be applied.

Function sotid_inq makes an inquiry of the current SOTID configuration and returns the status. One inquiry at the time can be made. sotid_inq returns the value of the requested parameter as well as the output string with description. The following requests are recognized:

: SOTID__REQ_MODEL_2D -- what is the model for computation of the tides of the second degree.
: SOTID__REQ_MODEL_3D -- what is the model for computation of the tides of the third degree.
: SOTID__REQ_GEN_LOVE -- which generalized Love numbers to take into account.
: SOTID__REQ_ORDER_2D -- waves of which order, degree 2 to take into account.
: SOTID__REQ_ZF_LOVE -- what is the model for Love numbers for the zero frequency.
: SOTID__REQ_N_STA -- for how many stations STATID records were set up.
: SOTID__REQ_NW_D2 -- how many tidal waves of the potential degree 2 are used.
: SOTID__REQ_NW_D3 -- how many tidal waves of the potential degree 3 are used.

Subroutine sotid_pre computes time-independent arguments used for computations of site displacements caused by the solid Earth tides. These arguments depend on crust-fixed station positions. Routine sotid_pre puts these time-independent arguments into the STATID arrays.

Subroutine sotid_tim calculates intermediary time-dependent sums over harmonics of the tidal potential of the second and the third degree. These quantities are used in computation of the displacements due to the Earth solid tides, pole tides and ocean loading. They are put in the object TIDCNF. Routine SOTID_TIM should be called each time for the new moment of time before SOTID_DSP which computes tidal displacement for the specific moment of time specified in the call to SOTID_TIM for the specific station. Truncated harmonic expansion HW95 is used for computation.

Subroutine sotid_dsp computes site displacements due to the Earth's solid tides of the second and third degree using harmonic expansion of tidal potential according to the configuration parameters of sotid. It is assumed that session-dependent and time-dependent intermediary quantities were calculated before by calls of sotid_set, sotid_pre and sotid_tim.

FILES

Package sotid is compiled with include files which keep coefficients of the truncated harmonic expansion of the tide-generating potential. This expansion is derived from the hw95 expansion in Poisson series. Names of the files with these coefficients are defined during compilation and kept in sotid_data.i include file. The files with these coefficients may be created with using program hw95_out which is the part of sotid. hw95_out will require original file of Hartmann-Wenzel expansion hw95. This file is not distributed with sotid and can be downloaded from http://bowie.gsfc.nasa.gov/hw95/

AUTHOR

Leonid Petrov ( pet@leo.gsfc.nasa.gov )

: Last update: 2002.07.17

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Time: 22:44:40 GMT, February 11, 2005